A thin rectangular piece of wood floats in water. You slowly pour oil with a density equal to that of the wood on the surface of the water until the height of the oil above the water is twice the height of the piece of wood. Which statement is correct?
a. The wood floats on top of the oil, so it sticks up in the air.
b. The wood does not change its position
c. The wood sinks below the surface of the water.
d. The wood is half in the water and half in the oil.
e. The wood floats in the oil just above the water.
[Ques. 2] Water is sent from a firehose at 30.0 m/s at an angle of 30.0 above the horizontal. What is the maximum height reached by the water?
a. 7.50 m
b. 11.5 m
c. 15.0 m
d. 19.0 m
e. 30.0 m
[Ques. 3] How much power is theoretically available from a mass flow of 1000 kg/s of water when it falls a vertical distance of 100 meters?
a. 980 kW
b. 98 kW
c. 4900 W
d. 980 W
e. 9600 W
[Ques. 4] A wind of velocity 10 m/s is blowing through a wind generator with blade radius 5.00 meters. What is the maximum power output if 30.0 of the wind's energy can be extracted? air = 1.25 kg/m3.
a. 7.20 kW
b. 14.7 kW
c. 21.3 kW
d. 29.4 kW
e. 39.6 kW
[Ques. 5] A Venturi tube may be used as the inlet to an automobile carburetor. If the 2.0-cm diameter pipe narrows to a 1.0-cm diameter, what is the pressure drop in the constricted section for an airflow of 3.0 m/s in the 2.0-cm section? ( = 1.2 kg/m3.)
a. 70 Pa
b. 85 Pa
c. 100 Pa
d. 120 Pa
e. 81 Pa
[Ques. 6] A Boeing 737 airliner has a mass of 20,000 kg and the total area of both wings (top or bottom) is 100 m2 . What is the pressure difference between the top and bottom surface of each wing when the airplane is in flight at a constant altitude?
a. 1960 N/m2
b. 3920 N/m2
c. 7840 N/m2
d. 4560 N/m2
e. 3070 N/m2
[Ques. 7] Air within the funnel of a large tornado may have a pressure of only 0.2 atm. What is the approximate outward force on a (5 m 10 m) wall if a tornado suddenly envelops the house? (1 atm = 1.01 105 N/m2.)
a. 4 103 N
b. 4 104 N
c. 4 105 N
d. 4 106 N
e. 7 105 N
[Ques. 8] In a wind tunnel the pressure on the top surface of a model airplane wing is 8.8 104 N/m and the pressure on the bottom surface is 9.0 104 N/m2 . If the area of the top and bottom surfaces of each wing is 2.0 m2, what is the total lift on the model airplane?
a. 2.0 103 N
b. 8.0 103 N
c. 1.6 104 N
d. 3.6 104 N
e. 1.0 103 N
[Ques. 9] The pressure inside a commercial airliner is maintained at 1 atm (1.01 105 N/m2). What is the outward force exerted on a 1.0 m 2.0 m cabin door if the outside pressure (at 10-km height) is 0.3 atm?
a. 1.4 102 N
b. 1.4 103 N
c. 1.4 104 N
d. 1.4 105 N
e. 7.0 103 N
[Ques. 10] What is the net force inward acting on a spherical bathysphere of diameter 2.00 m at an ocean depth of 1000 m? (The pressure inside the bathysphere is, hopefully, 1 atm.) sea water = 1.02 103 kg/m3.
a. 1.26 104 N
b. 1.26 106 N
c. 1.26 108 N
d. 1.26 1010 N
e. 1.26 102 N
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